Field
The present disclosure relates generally to data networks, and more particularly to multicast data networks, and still more particularly to an intermediate unicast network for such multicast data networks.
Description of the Problem and Related Art
Many large retail company's “point-of-sale” [PoS] backbone is based on the vintage Toshiba ACE system using IBM 4960 servers. When this technology was released in the 1980's there was no way to predict how complex Ethernet networking architectures would operate in 2015. At the core of large retailer's internal network are often over 50,000 PoS units that require modernization of how they send, receive and interact with the rest of the corporate network.
The challenge is that these PoS devices transmit and receive using an antiquated method of “multicast,” data packets, typically using the long-used user datagram protocol (UDP) in the transport layer.
FIG. 1 illustrates a typical prior art network architecture 100 for such systems where a centralized computer-based server 101 disseminates data over an internetwork (internet) virtual private network (VPN) 103 to a plurality of remote, distributed local servers 105a-d located at retail outlets and which in turn convey the data to a plurality of distributed devices 109 a-e, which may be PoS registers. Generally, the data comprises inventory data representing inventory, for example, stock keeping unit (SKU) data, and pricing data for each SKU, including not only normal retail price but also any price discounts. In some instances, the central server 101 must provide data to over 50,000 registers 109, and this is executed each day because of constantly changing pricing and inventory within each retail outlet. The amount of data transmitted can be enormous.
Between the local servers 105a-d and the registers 109, the system 100 uses a multicast communication method, but one wherein all network hosts 109 hear all the data for all the hosts regardless of relevance to an individual host. To transmit data, the system 100 employs Multicast UDP packets as the data transport mechanism. Normally, multicast techniques are termed “one-to-many,” where, for example, a local server communicates with specific groups of hosts each of which share a specific multicast group identifier. Each host on the network receive all the data for all hosts but only allows data with the correct group identifier to enter into the host's operating system. All members of the multicast group on this network 100 are expected by the server to receive the group's data regarding pricing and inventory. Although, each register 109 is singular, it is designated as a member of a multicast group. Unfortunately, the network can become saturated with huge amounts of unneeded data transfers due to multicast protocol's inherently wasteful technique of sending all the data for all the groups to all the registers on the network.
Multicast packet transfers data use UPD/IP protocol. UDP protocol uses a simple connectionless transmission model with a minimum of protocol mechanism and has no handshaking or packet acknowledgment dialogues. An illustration of a UDP data packet 301 is shown in FIG. 3B and comprises a UDP/IP header 305 and a payload 307 (data). Multicast UDP/IP is inherently unreliable because there is no acknowledgment of delivery, packet retransmission, packet ordering, or duplicate packet protection. Because of these shortcomings any multicast group member may fail to receive all of the group's inventory and pricing data, which causes the data transfer for the entire multicast group K to be terminated and then restarted again at the beginning to insure all multicast groups 109a-e receive the full data transfer. It is common that several restarts may be required for all group members to receive the entire transfer. This can result in unnecessary boot up delays and in larger networks, may result in data overflows within the local network, resulting in more lost packets which results in more transfer restarts which results in more saturation.
This is an unscalable, inefficient and unreliable method for communication on a modern network. The currently deployed infrastructure of these PoS devices is massive with some PoS systems as old as 20 years. New PoS systems still use this method today and there is no foreseeable end-of-life to this antiquated PoS communications “standard”.